BackgroundThe 2010 influenza vaccination program for children aged 6 months to 4 years in Western Australia (WA) was suspended following reports of severe febrile reactions, including febrile convulsions, following vaccination with trivalent inactivated influenza vaccine (TIV).MethodsTo investigate the association between severe febrile reactions and TIV, three studies were conducted: (i) rates of febrile convulsions within 72 h of receiving TIV in 2010 were estimated by vaccine formulation and batch; (ii) numbers of children presenting to hospital emergency departments with febrile convulsions from 2008 to 2010 were compared; and (iii) a retrospective cohort study of 360 children was conducted to compare the reactogenicity of available TIV formulations.FindingsIn 2010, an estimated maximum of 18 816 doses of TIV were administered and 63 febrile convulsions were recorded, giving an estimated rate of 3.3 (95% CI 2.6 to 4.2) per 1000 doses of TIV administered. The odds of a TIV-associated febrile convulsion was highly elevated in 2010 (p<0.001) and was associated with the vaccine formulations of one manufacturer—Fluvax and Fluvax Junior (CSL Biotherapies). The risk of both febrile convulsions (p<0.0001) and other febrile reactions (p<0.0001) was significantly greater for Fluvax formulations compared to the major alternate brand. The risk of febrile events was not associated with prior receipt of TIV or monovalent 2009 H1N1 pandemic vaccine. The biological cause of the febrile reactions is currently unknown.InterpretationOne brand of influenza vaccine was responsible for the increase in febrile reactions, including febrile convulsions. Until the biological reason for this is determined and remediation undertaken, childhood influenza vaccination programs should not include Fluvax-type formulations and enhanced surveillance for febrile reactions in children receiving TIV should be undertaken.

Introduction

Aim To explore immunisation rates and catch‐up delivery to children admitted to hospital before and after an immunisation service was commenced. Methods This pre‐ and post‐intervention study examined 300 admissions prior to (cohort 1) and 300 following (cohort 2) the introduction of an immunisation service. Immunisation rates, documentation, catch‐up delivery and accuracy of the Australian Immunisation Register (AIR) were examined. Results On admission, 75% (cohort 1) and 89% (cohort 2) were up‐to‐date with immunisations. Immunisation history was documented in the medical record in 78% and requirement for catch‐up documented in 10%. AIR was incorrect in one‐third of cases. By 3 months following discharge, 28% (cohort 1) and 64% (cohort 2) of patients were immunised. Conclusions Children admitted to hospital have lower immunisation rates than the national average. Documentation was poor, opportunities for catch‐up were missed and AIR is error‐prone. Catch‐up rates increased following the introduction of an immunisation service.

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